1. Field of the Invention
The invention relates to a method and apparatus for forming plastic articles. Specifically, the invention relates to a method and apparatus for welding a semirigid bead to two sheets of plastic film.
2. Description of Related Art
Plastic articles made from two or more sheets or plies of plastic material are commonly manufactured for use as bags, gloves, and other devices. Many of these plastic articles have rims or beads molded or attached to their open ends. When the plastic articles are used as medical devices, their method and apparatus for manufacture must provide a consistently high quality article that does not tear at the joinder of the film with the bead and that is not abrasive when rubbed against the skin.
U.S. Pat. No. 2,900,779 to Baxter et al. discloses a tool for opening and expanding the mouth of a flexible receptacle. The device of this patent assembles a "supporting neck ring" to a "flexible and somewhat stretchable film material." This device is not designed to open a multiple ply plastic article and also apply it over the ring before welding the two elements together.
U.S. Pat. No. 3,247,647 to Koch discloses an applicator device. The device of this patent applies a bag over a rigid tubular holder to form a baby bottle. This device does not apply a multiple ply plastic article over a ring before welding the two elements together.
The industry lacks a high speed method and apparatus for applying a bead or ring to an open end of a multiple ply plastic article such as a bag or contraceptive device.